1. Technical Field
The present disclosure relates to a particle sensor.
2. Description of the Related Art
Known particle sensors include a scattered light particle sensor that uses scattered light to detect airborne particles (aerosol).
A scattered light particle sensor is a photoelectric sensor including a light projector and a light receiver, and emits light via the light projector into gas introduced into the sensor as a target to be measured and detects particles in the gas by detecting light scattered by the particles. With this, airborne dust, pollen, smoke, and PM 2.5 (fine particulate matter), for example, can be detected.
There is a problem with scattered light particle sensors that a portion of the light from the light projector becomes stray light (unwanted light) and reaches the light receiver, decreasing detection accuracy. A technique has been proposed that disposes a light trap (stray light trap) so as to oppose the light projector or the light receiver to reduce stray light (for example, see Japanese Unexamined Patent Application Publication No. H11-248629 and Japanese Unexamined Patent Application Publication No. 2000-235000).